EP1247280B1 - Equipment for imaging by spect - Google Patents
Equipment for imaging by spect Download PDFInfo
- Publication number
- EP1247280B1 EP1247280B1 EP01900144A EP01900144A EP1247280B1 EP 1247280 B1 EP1247280 B1 EP 1247280B1 EP 01900144 A EP01900144 A EP 01900144A EP 01900144 A EP01900144 A EP 01900144A EP 1247280 B1 EP1247280 B1 EP 1247280B1
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- EP
- European Patent Office
- Prior art keywords
- collimator
- bed
- detector
- patient
- equipment
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
- G21K1/025—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
- G01T1/164—Scintigraphy
- G01T1/1641—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
- G01T1/1648—Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices
Definitions
- the invention relates to a collimator for use in the method of imaging a target organ in a patient by SPECT, to a combination of a gamma detector and a collimator, and to a gamma camera, provided with said combination.
- the invention also relates to an equipment for performing the method of imaging a target organ in a patient by SPECT, by using the so-called LOrA technique, which equipment comprises at least one detector-combined collimator.
- SPECT Single Photon Emission Computed Tomography
- SPECT is performed by using a gamma camera, comprising a collimator fixed on a gamma detector, which gamma camera follows a revolution orbit around the patient's body.
- the gamma rays, emitted by a radioactive tracer, accumulated in certain tissues or organs of the patient's body, are sorted by the collimator and recorded by the gamma detector under various angles around the body, the collimator always pointing to (facing) the rotation axis of the camera. From the acquired planar images the distribution of the activity inside the patient's body can be computed using certain reconstruction algorithms.
- the collimators nowadays in use are manufactured from a lead sheat perforated with a plurality of usually parallel holes.
- the collimator is the most problematic element of the SPECT device, with regard to its poor sensitivity (less than 0.01% of the gamma radiation passes the collimator and reaches the detector) and its poor spatial resolution, becoming increasingly worse with increasing distance between activity source (i.e. the organ or tissue wherein the radioactivity has been accumulated) and collimator. Improvement of one of these properties, e.g. by modifying the hole length or diameter of the collimator, is always to the detriment of the other one. Furthermore, the SPECT technique is inadequate in producing reliable images because of the fact that small fluctuations in the acquired data can involve significant variations in the reconstructed images.
- a so-called rake collimator which comprises, in addition to a plurality of collimator septa in a mutually parallel arrangement, at least one raised wall, considerably larger than the septa and transversally positioned thereto.
- the collimator is outwards provided with one or two raised walls.
- this wall preferably extends perpendicularly from a common central line of the septa.
- these walls are preferably slanted inwards from the ends of the septa to form, in cross section, the sides of a trapezium with a topline-length of approx. 3 to approx. 12 mm.
- gamma cameras for SPECT imaging are often adapted to the special organs to be studied (organ-dedicated), for example, head-dedicated equipment for specific study of the head (by using an annular camera), etc.
- organ-dedicated for example, head-dedicated equipment for specific study of the head (by using an annular camera), etc.
- the heigth of the septa is normally 3 or 4 cm. If in the method of the invention head-dedicated cameras are preferred, such cameras have only to be equipped with rake collimators, having said at least one raised wall extending beyond said septa over a distance of approx. 8 or 9 cm, measured perpendicularly with respect to the outer surface of the detector.
- Rake collimators having said at least one raised wall extending beyond said septa over a maximum distance of approximately 26 cm, preferably of between 16 and 22 cm, measured perpendicularly with respect to the outer surface of the detector, can be used generally, i.e. both for the whole body and for organ-dedicated SPECT imaging.
- the above raised wall should be manufactured from a suitable material, preferably from a high-attenuating material, such as tungsten, lead, gold, tantalum, platinum or iridium. From a cost-performance point of view, tungsten is extremely suitable for this purpose.
- the present invention relates to a combination of a gamma detector and a rake collimator, as defined above, wherein the collimator extends outwards in the longitudinal direction of the detector, and to a gamma camera, provided with a combination of a gamma detector and said above-defined collimator.
- the sensitivity-resolution couple of the collimator can be improved substantially by using a fan-beam collimator, focusing to a focal line parallel to the patient's body length, which focal line is made to travel through the target organ during the acquisition of the images.
- This acquisition is performed along one or a plurality of linear orbits (paths) in a direction perpendicular to the patient's body length, and is called the Linear Orbital Acquisition (LOrA) technique.
- LLOrA Linear Orbital Acquisition
- the invention also relates to an equipment for performing the above method of SPECT imaging by using the so-called LOrA technique, comprising at least one gamma camera with at least one detector-combined collimator, and a bed for a patient to be examined in such a relative position, that the bed is surrounded by four collimator positions, essentially situated at the angular points of a square (which are only for simplicity reasons chosen to be situated over the bed ( a ), under the bed ( b ), and on both sides ( c ) and ( d ) of the bed), which positions can be occupied by said at least one collimator.
- the patient to be examined is fixedly positioned on a bed.
- the equipment for performing the above method of imaging by SPECT is characterized in that:
- the outer edge (extremity) of said collimator's raised wall should be positioned as close as possible to the patient's body, to improve the sensitivity and resolution of the system.
- the minimum distance between said extremity and said body depends on the portion of the body (or on the organ) to be examined, but is generally less than approx. 5 cm, preferably, however, approx. 1 cm at most.
- images can be acquired by the gamma camera along four linear orbits performed in mutually transverse directions perpendicular to the patient's body.
- the range of the relative movements of the bed vis-à-vis the collimator or collimators should preferably be at least equal to two times the transverse size of the detector or collimator.
- the rake collimator(s) forming part of the equipment of the invention has (have) advantageously at least one raised wall, extending beyond the collimator septa over a distance of between approx. 8 and approx. 26 cm. If allround, i.e. not dedicated to the imaging of certain target organs or parts of the body like the head, this length is preferably between 16 and 22 cm (see above).
- the equipment according to the present invention may conveniently comprise one gamma detector provided with a rake collimator.
- a detector-collimator combination is equipped in such manner that it can be moved from the above-defined position ( a ) to positions ( c ), (b) and ( d ), successively, and vice versa.
- a second gamma detector provided with a rake collimator into the equipment of the present invention.
- the two detector-collimator combinations are positioned opposite to each other, sandwiching bed plus patient in between, both equipped in such manner that they can be moved from position ( a ) to position ( c ), and from position ( b ) to position ( d ), respectively, and vice versa.
- the equipment is preferably so adapted that the bed is movable vis-à-vis the collimator by means of a system of motive members, preferably a combination of a horizontally shifting mobile member at the foot of the bed and a jack for moving the bed into a vertical direction.
- a system of motive members preferably a combination of a horizontally shifting mobile member at the foot of the bed and a jack for moving the bed into a vertical direction.
- the equipment of the present invention comprises four gamma detectors with rake collimators, which detector-collimator combinations are so positioned that they occupy positions ( a ), ( b ), ( c ) and ( d ), respectively, thereby sandwiching bed plus patient in between.
- the four detector-collimator combinations are preferably movable vis-à-vis the bed by means of a motive system, preferably a rigid frame of four mutually perpendicular rails, positioned transversally to the bed length, along which the detector-collimator combinations can slide. This motive system is also explained in the Examples.
- the relative movements of the bed vis-à-vis the detector-collimator combination(s) can be computer controlled (cybernation) by the gamma camera.
- This advanced system of computer-driven detector-collimator combination(s) relative to the patient's bed enables the user of the system, i.e. the personnel of the clinic or hospital, to examine the patient full-automatically by the improved SPECT imaging technique of the invention.
- the usable transverse size dimension of the SPECT device can be fully used, i.e. the target organ size has to be equal at most to the detector transverse size, to acquire a complete set of planar images (i.e. sufficient to reconstruct the activity distribution).
- a collimator with said at least one raised wall outwards extending from the gamma detector's outer surface, i.e. the surface facing the patient during use, a considerable improvement of the sensitivity-resolution couple can be obtained, even a further improvement with regard to that described in the above WO 99/09431 .
- target organ is not only meant the organ or tissue to be studied or investigated by using the above method, but obviously encompasses a plurality of organs to be studied simultaneously and also a part of the body, like the head, the chest or the abdomen, or even the complete body of the patient. It is further important to note, that the linear orbits or paths must not necessarily be straight lines, but also encompass slightly curved lines.
- Figures 1 and 2 show a gamma detector 1 equipped with a rake collimator 2, comprising a plurality of collimator septa 24 and a raised wall 23, as described hereinafter.
- the detector-collimator combination is movably attached to a circular rail 3 held by two pylons 9.
- the detector 1 can move along the rail, the longitudinally positioned raised wall 23 of the collimator 2 always pointing to the rotation axis 8.
- the detector 1 can be positioned over, under, left and right the bed 4: positions a , b , c and d , respectively (the collimator centres are situated at the angular points of a square).
- a motor attached to the detector 1 and drawing an endless screw acting on a circular rack attached along the rail 3 can be used to move the detector-collimator combination from one position into another.
- the bed 4 can vertically move thanks to the jacks 5, which can be constituted by a motorized endless screw acting on a rack.
- a crenelated plate drawing by the endless screw and inserted in an optical switch can be used to adjust the vertical position of the bed 4.
- This bed can also move along the left - right direction of Figure 1 (horizontal transverse direction) thanks to the mobile element 7 which can be a trolley rolling along a rail on the floor.
- a motorized endless screw acting on a rack and drawing a crenelated plate inserted in an optical switch can be used to move and adjust the transverse horizontal bed 4 position.
- the vertical positioning range of the bed 4 vis-à-vis the rotation axis 8 should be optimal with respect to the equipment used, the horizontal positioning range is at least equal to two times the transverse size 6 of the detector 1.
- the raised wall 23 is parallel to the bed 4 length and points to the rotation axis 8, said axis corresponding with a central line through the patient's body on the bed 4.
- the distance between the outer edge (extremity) 27 of the raised wall 23 and the body surface is as small as possible, preferably approx. 1 cm at most.
- the planar images are digitally acquired along four linear orbits: the bed 4 is moved into the various successive vertical positions, when the detector 1 is unmoved left or right the bed 4 (in positions c or d , respectively); the bed is moved into the various successive transverse horizontal positions, when the detector 1 is unmoved over or under the bed 4 (in positions a or b , respectively).
- the digital planar images and the vertical and horizontal digital bed 4 positions are sent to the treatment computer.
- the distribution of the radioactivity over the patient's body A(x,y,z), wherein x,y and z are the orthogonal coordinates along the horizontal transverse direction, the vertical direction and the longitudinal direction, respectively, can be computed using the new reconstruction algorithm as disclosed hereinbefore.
- a second detector - rake collimator combination may be present in position b of the above equipment, movable along the rail 3 from position b to position d and vice versa , whereas the first combination is then movable from position a to position c and vice versa.
- the embodiment shown in Figure 3 comprises four gamma detectors 11a, 11b, 11c and 11d, provided with rake collimators 12a, 12b, 12c and 12d (raised walls not shown), situated over, under, left and right the bed 14 (positions a , b , c and d , respectively).
- Each detector can be moved along a rail (13a, 13b, 13c and 13d), perpendicular to the bed 14 length; the rails are attached to each other to constitute a rigid frame.
- the detector-collimator combinations move along their rails, the bed being unmoved.
- FIGs 4 through 9 show schematically a gamma detector 1 with two different rake collimators 2 and 2a in more detail.
- the rake collimator of figures 4-6 is composed of a raised wall 23, parallel to the longitudinal direction 25 of the detector, and of a plurality of collimator septa 24, perpendicular to the raised wall and parallel to the transverse direction 26 of the detector.
- the heigh of the collimator septa is approx. 3 or 4 cm, that of the raised wall approx. 20-25 cm, both measured from the outer surface of the gamma detector.
- the rake collimator of figures 7-9 is, in addition to the collimator septa 24, provided with two raised walls 23a,b, positioned at both outer edges of the detector and slanted inwards.
- these raised walls form the sides of a trapezium with a topline-length t of between 3 and 12 mm.
- the raised walls are manufactured from tungsten.
- the outer edges of the raised walls 23 and 23a,b extend from the outer surface of the gamma detector 1 over a distance of approx. 20 to 25 cm, measured perpendicularly with respect to said outer surface.
- the collimator septa extend from said detector's outer surface over a distance of approx. 3 or 4 cm.
- the method of the present invention is performed with the radiation source situated at a distance of less than 1 cm from the rake collimator's outer edge (extremity). After a suitable acquisition time, the SPECT spatial resolution of figure 10 is obtained. From this figure it can be concluded, that the spatial resolution obtained according to the method of the invention is surprisingly good, without any degradation at increasing distance from the collimator.
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Abstract
Description
- The invention relates to a collimator for use in the method of imaging a target organ in a patient by SPECT, to a combination of a gamma detector and a collimator, and to a gamma camera, provided with said combination.
The invention also relates to an equipment for performing the method of imaging a target organ in a patient by SPECT, by using the so-called LOrA technique, which equipment comprises at least one detector-combined collimator. - The Single Photon Emission Computed Tomography (SPECT) is routinely used in clinical studies. SPECT is performed by using a gamma camera, comprising a collimator fixed on a gamma detector, which gamma camera follows a revolution orbit around the patient's body. The gamma rays, emitted by a radioactive tracer, accumulated in certain tissues or organs of the patient's body, are sorted by the collimator and recorded by the gamma detector under various angles around the body, the collimator always pointing to (facing) the rotation axis of the camera. From the acquired planar images the distribution of the activity inside the patient's body can be computed using certain reconstruction algorithms. Generally the so-called Expectation-Maximization of the Maximum-Likelihood (EM-ML) algorithm is used, as described by Shepp et al. (IEEE Trans. Med. Imaging 1982; 2:113-122) and by Lange et al. (J. Comput. Assist. Tomogr. 1984; 8:306-316). This iterative algorithm minimizes the effect of noise in SPECT images.
- The collimators nowadays in use are manufactured from a lead sheat perforated with a plurality of usually parallel holes. The collimator is the most problematic element of the SPECT device, with regard to its poor sensitivity (less than 0.01% of the gamma radiation passes the collimator and reaches the detector) and its poor spatial resolution, becoming increasingly worse with increasing distance between activity source (i.e. the organ or tissue wherein the radioactivity has been accumulated) and collimator. Improvement of one of these properties, e.g. by modifying the hole length or diameter of the collimator, is always to the detriment of the other one. Furthermore, the SPECT technique is inadequate in producing reliable images because of the fact that small fluctuations in the acquired data can involve significant variations in the reconstructed images. This is due to the geometry of the acquired data. The limited time available for obtaining the necessary information (because of the restricted fixation time of the patient and the decay time of the radioactive tracer) and the limited injected radioactivity dose (limited for health care reasons) lead to acquired images containing statistical noise. Indeed the measurement of a radioactive process follows the Poisson law, giving a signal to noise ratio proportional to the square root of the count rate. As a result, the reconstructed images are frequently corrupted by significant false positive information, so-called noise artefacts. Consequently, it is a major goal in SPECT imaging to increase the SPECT sensitivity without reduction of the spatial resolution in order to improve the acquired signal to noise ratio.
- Therefore it is the objective of the present invention to provide an improved equipment for performing the method of imaging a target organ by SPECT.
This objective can be achieved, according to the present invention, by using in said equipment a so-called rake collimator, which comprises, in addition to a plurality of collimator septa in a mutually parallel arrangement, at least one raised wall, considerably larger than the septa and transversally positioned thereto.
Surprisingly it has been found, that by using such a rake collimator in combination with a gamma detector, wherein said at least one raised wall of the collimator extends outwards in the longitudinal direction of the detector, a considerable improvement of the sensitivity-resolution couple can be obtained. - Preferably the collimator is outwards provided with one or two raised walls.
In case the collimator is provided with a single raised wall, this wall preferably extends perpendicularly from a common central line of the septa.
In case the collimator is provided with two raised walls, these walls are preferably slanted inwards from the ends of the septa to form, in cross section, the sides of a trapezium with a topline-length of approx. 3 to approx. 12 mm. - To improve their results, gamma cameras for SPECT imaging are often adapted to the special organs to be studied (organ-dedicated), for example, head-dedicated equipment for specific study of the head (by using an annular camera), etc. The heigth of the septa is normally 3 or 4 cm. If in the method of the invention head-dedicated cameras are preferred, such cameras have only to be equipped with rake collimators, having said at least one raised wall extending beyond said septa over a distance of approx. 8 or 9 cm, measured perpendicularly with respect to the outer surface of the detector. Rake collimators, having said at least one raised wall extending beyond said septa over a maximum distance of approximately 26 cm, preferably of between 16 and 22 cm, measured perpendicularly with respect to the outer surface of the detector, can be used generally, i.e. both for the whole body and for organ-dedicated SPECT imaging.
- The above raised wall should be manufactured from a suitable material, preferably from a high-attenuating material, such as tungsten, lead, gold, tantalum, platinum or iridium. From a cost-performance point of view, tungsten is extremely suitable for this purpose.
- Further the present invention relates to a combination of a gamma detector and a rake collimator, as defined above, wherein the collimator extends outwards in the longitudinal direction of the detector, and to a gamma camera, provided with a combination of a gamma detector and said above-defined collimator.
- In the published Intern. Patent Application no.
WO 91/00048
According to the published Intern. Patent application no.WO 99/09431 - Therefore the invention also relates to an equipment for performing the above method of SPECT imaging by using the so-called LOrA technique, comprising at least one gamma camera with at least one detector-combined collimator, and a bed for a patient to be examined in such a relative position, that the bed is surrounded by four collimator positions, essentially situated at the angular points of a square (which are only for simplicity reasons chosen to be situated over the bed (a), under the bed (b), and on both sides (c) and (d) of the bed), which positions can be occupied by said at least one collimator. The patient to be examined is fixedly positioned on a bed. According to the present invention, the equipment for performing the above method of imaging by SPECT is characterized in that:
- said detector-combined collimator is a rake collimator as defined hereinbefore, having its at least one raised wall parallel to the bed length;
- the bed is positioned at such a distance from the collimator positions, that in each position the outer edge (extremity) of said collimator's raised wall is approx. 5 cm distanced at most from the patient's body on the bed; and
- the bed is adapted to allow movements vis-à-vis said at least one collimator in two perpendicular directions, both transverse to the bed length, viz. a sideward movement at position (a) or (b) of said at least one collimator and an up and downward movement at position (c) or (d) thereof; or, alternatively, said at least one collimator is adapted to allow movements vis-à-vis the bed in perpendicular directions, all transverse to the bed length, viz. substantially parallel to the bed surface in the positions (a) and (b), and substantially perpendicular to the bed surface in the positions (c) and (d)
- The outer edge (extremity) of said collimator's raised wall should be positioned as close as possible to the patient's body, to improve the sensitivity and resolution of the system. The minimum distance between said extremity and said body depends on the portion of the body (or on the organ) to be examined, but is generally less than approx. 5 cm, preferably, however, approx. 1 cm at most. By positioning the bed at such a distance from the rake collimator positions (this positioning can be adjusted by a computer, preferably by the acquisition computer), in each of these positions the rake collimator's raised wall remains as closest as possible to the patient's body on the bed during the acquisition by the gamma camera along linear orbits. By adapting the bed or the rake collimator in such manner that it allows relative perpendicularly directed movements, as described above, images can be acquired by the gamma camera along four linear orbits performed in mutually transverse directions perpendicular to the patient's body.
- The range of the relative movements of the bed vis-à-vis the collimator or collimators should preferably be at least equal to two times the transverse size of the detector or collimator. The rake collimator(s) forming part of the equipment of the invention has (have) advantageously at least one raised wall, extending beyond the collimator septa over a distance of between approx. 8 and approx. 26 cm. If allround, i.e. not dedicated to the imaging of certain target organs or parts of the body like the head, this length is preferably between 16 and 22 cm (see above).
- It should be emphasized that by the expression "at least one" should be understood: one up to four; more in particular: one, two or four.
So the equipment according to the present invention may conveniently comprise one gamma detector provided with a rake collimator. Such a detector-collimator combination is equipped in such manner that it can be moved from the above-defined position (a) to positions (c), (b) and (d), successively, and vice versa. - It may be of advantage, however, to include a second gamma detector provided with a rake collimator into the equipment of the present invention. In that case the two detector-collimator combinations are positioned opposite to each other, sandwiching bed plus patient in between, both equipped in such manner that they can be moved from position (a) to position (c), and from position (b) to position (d), respectively, and vice versa.
In case one or two detector-collimator combinations are present in the equipment of the invention, the equipment is preferably so adapted that the bed is movable vis-à-vis the collimator by means of a system of motive members, preferably a combination of a horizontally shifting mobile member at the foot of the bed and a jack for moving the bed into a vertical direction. This system of motive members is explained in more detail in the Examples. - In an equally advantageous embodiment the equipment of the present invention comprises four gamma detectors with rake collimators, which detector-collimator combinations are so positioned that they occupy positions (a), (b), (c) and (d), respectively, thereby sandwiching bed plus patient in between.
In this embodiment the four detector-collimator combinations are preferably movable vis-à-vis the bed by means of a motive system, preferably a rigid frame of four mutually perpendicular rails, positioned transversally to the bed length, along which the detector-collimator combinations can slide. This motive system is also explained in the Examples. - It is another merit of the equipment of the present invention that the relative movements of the bed vis-à-vis the detector-collimator combination(s) can be computer controlled (cybernation) by the gamma camera. This advanced system of computer-driven detector-collimator combination(s) relative to the patient's bed enables the user of the system, i.e. the personnel of the clinic or hospital, to examine the patient full-automatically by the improved SPECT imaging technique of the invention.
- By using in the method of imaging by SPECT according to the LOrA technique the above defined equipment of the invention, which is a better accessible equipment as described in the above
WO 99/09431 - In the above method the usable transverse size dimension of the SPECT device can be fully used, i.e. the target organ size has to be equal at most to the detector transverse size, to acquire a complete set of planar images (i.e. sufficient to reconstruct the activity distribution).
Surprisingly it has been found, that by using in the above tomographic method a collimator with said at least one raised wall, outwards extending from the gamma detector's outer surface, i.e. the surface facing the patient during use, a considerable improvement of the sensitivity-resolution couple can be obtained, even a further improvement with regard to that described in the aboveWO 99/09431 WO 99/09431 - Preferably, in the above method the longitudinal length of the gamma detector (= the length of said raised wall) is larger than the thickness of the transverse slices of the patient's body to be imaged and reconstructed.
- It should be emphasized, that by the term "target organ" is not only meant the organ or tissue to be studied or investigated by using the above method, but obviously encompasses a plurality of organs to be studied simultaneously and also a part of the body, like the head, the chest or the abdomen, or even the complete body of the patient.
It is further important to note, that the linear orbits or paths must not necessarily be straight lines, but also encompass slightly curved lines. - The invention will now be described in greater detail with reference to the accompanying drawings, wherein:
- Figures 1 and 2 are schematic representations of the equipment according to the present invention in a suitable embodiment, Fig. 1 viewed in the longitudinal direction of the bed and Fig. 2 viewed in a direction transverse to the bed;
- Figure 3 is also a schematic representation of such an equipment of the present invention, now in another suitable embodiment, viewed in the longitudinal direction of the bed, as in Fig. 1;
- Figures 4 through 9 show two suitable embodiments of a gamma detector equipped with a rake collimator to be used in the above equipment, figures 4 and 7 in perspective view, figures 5 and 8 viewed from above, and figures 6 and 9 in side-view; and
- Figure 10 shows a SPECT spatial revolution image, obtained by performing a model experiment.
- Figures 1 and 2 show a
gamma detector 1 equipped with arake collimator 2, comprising a plurality ofcollimator septa 24 and a raisedwall 23, as described hereinafter. The detector-collimator combination is movably attached to acircular rail 3 held by twopylons 9. Thedetector 1 can move along the rail, the longitudinally positioned raisedwall 23 of thecollimator 2 always pointing to the rotation axis 8. Using a magnetic brake, thedetector 1 can be positioned over, under, left and right the bed 4: positions a, b, c and d, respectively (the collimator centres are situated at the angular points of a square). A motor attached to thedetector 1 and drawing an endless screw acting on a circular rack attached along therail 3 can be used to move the detector-collimator combination from one position into another. Thebed 4 can vertically move thanks to thejacks 5, which can be constituted by a motorized endless screw acting on a rack. A crenelated plate drawing by the endless screw and inserted in an optical switch can be used to adjust the vertical position of thebed 4. This bed can also move along the left - right direction of Figure 1 (horizontal transverse direction) thanks to themobile element 7 which can be a trolley rolling along a rail on the floor. Again a motorized endless screw acting on a rack and drawing a crenelated plate inserted in an optical switch can be used to move and adjust the transversehorizontal bed 4 position. The vertical positioning range of thebed 4 vis-à-vis the rotation axis 8 should be optimal with respect to the equipment used, the horizontal positioning range is at least equal to two times thetransverse size 6 of thedetector 1. The raisedwall 23 is parallel to thebed 4 length and points to the rotation axis 8, said axis corresponding with a central line through the patient's body on thebed 4. The distance between the outer edge (extremity) 27 of the raisedwall 23 and the body surface is as small as possible, preferably approx. 1 cm at most. The planar images are digitally acquired along four linear orbits: thebed 4 is moved into the various successive vertical positions, when thedetector 1 is unmoved left or right the bed 4 (in positions c or d, respectively); the bed is moved into the various successive transverse horizontal positions, when thedetector 1 is unmoved over or under the bed 4 (in positions a or b, respectively). During acquisition, the digital planar images and the vertical and horizontaldigital bed 4 positions are sent to the treatment computer. The distribution of the radioactivity over the patient's body A(x,y,z), wherein x,y and z are the orthogonal coordinates along the horizontal transverse direction, the vertical direction and the longitudinal direction, respectively, can be computed using the new reconstruction algorithm as disclosed hereinbefore.
A second detector - rake collimator combination may be present in position b of the above equipment, movable along therail 3 from position b to position d and vice versa, whereas the first combination is then movable from position a to position c and vice versa. - The embodiment shown in Figure 3 comprises four
gamma detectors rake collimators bed 14 length; the rails are attached to each other to constitute a rigid frame.
During the acquisition the detector-collimator combinations move along their rails, the bed being unmoved. - Figures 4 through 9 show schematically a
gamma detector 1 with twodifferent rake collimators 2 and 2a in more detail. The rake collimator of figures 4-6 is composed of a raisedwall 23, parallel to thelongitudinal direction 25 of the detector, and of a plurality ofcollimator septa 24, perpendicular to the raised wall and parallel to thetransverse direction 26 of the detector. The heigh of the collimator septa is approx. 3 or 4 cm, that of the raised wall approx. 20-25 cm, both measured from the outer surface of the gamma detector.
The rake collimator of figures 7-9 is, in addition to thecollimator septa 24, provided with two raisedwalls 23a,b, positioned at both outer edges of the detector and slanted inwards. In cross section (fig. 9) these raised walls form the sides of a trapezium with a topline-length t of between 3 and 12 mm.
The raised walls are manufactured from tungsten. The outer edges of the raisedwalls gamma detector 1 over a distance of approx. 20 to 25 cm, measured perpendicularly with respect to said outer surface. The collimator septa extend from said detector's outer surface over a distance of approx. 3 or 4 cm. - To acquire real acquisition data, a model experiment has been carried out. In such an experiment the following requirements as to the equipment should be met:
- (a) camera plus suitable rake collimator,
- (b) suitable radiation source; and
- (c) camera plus collimator should be movable vis-à-vis the radiation source or vice versa.
- Ad (a). A suitable rake collimator, meeting the requirements of the present invention, namely a collimator corresponding to the figures 4-6 embodiment, has been manufactured. The raised wall, made of tungsten, extends from the outer surface of the gamma detector over a distance of 20 cm. The NaI crystal spatial resolution of the detector is 3 mm.
- Ad (b). As the radiation source is used a so-called Jaszczak's de luxe phantom, well-known in the art of performing radioactive experiments.
- Ad (c). The radiation source is movable relative to the collimator in such manner that it enables the acquisition of images along linear orbits performed in two directions x and y (horizontal and vertical), perpendicular to the SPECT camera rotation axis z.
- In the above arrangement, the method of the present invention is performed with the radiation source situated at a distance of less than 1 cm from the rake collimator's outer edge (extremity). After a suitable acquisition time, the SPECT spatial resolution of figure 10 is obtained.
From this figure it can be concluded, that the spatial resolution obtained according to the method of the invention is surprisingly good, without any degradation at increasing distance from the collimator.
Claims (11)
- A collimator for use in the method of imaging a target organ in a patient by SPECT, characterized in that the collimator (2, 2a), a so-called rake collimator, comprises, in addition to a plurality of collimator septa (24) in a mutually parallel arrangement, at least one raised wall (23), considerably larger than the septa and transversally positioned thereto.
- Collimator as claimed in claim 1, characterized in that said rake collimator comprises either a single raised wall (23), perpendicularly extending from a common central line of said septa (24), or two raised walls (23a, 23b), slanted inwards from the ends of said septa to form, in cross section, the sides of a trapezium with a topline-length (t) of from approx. 3 to approx. 12 mm.
- Collimator as claimed in any of claims 1-2, characterized in that at least one raised wall extends beyond said septa over a distance of between approx. 8 and approx. 26 cm, preferably of between 16 and 22 cm, measured perpendicularly with respect to the outer surface of the detector.
- Collimator as claimed in any of claims 1-3, characterized in that said at least one raised wall is manufactured from a high-attenuating material, preferably from tungsten, lead, gold, tantalum, platinum or iridium, more preferably from tungsten.
- A combination of a gamma detector and a collimator, wherein the collimator is defined in any of claims 1-4 and extends outwards in the longitudinal direction of the detector.
- A gamma camera, provided with a combination of a gamma detector and a collimator, wherein said combination is defined in claim 5.
- An equipment for performing the method of imaging a target organ in a patient by SPECT, by using the so-called LOrA technique, comprising at least one detector-combined collimator, a bed (4) for a patient to be examined, and means for defining four collimator positions relative to the bed, essentially situated at the angular points of a square, viz. over the bed (a), under the bed (b), and on both sides (c) and (d) of the bed, which positions can be occupied by said at least one collimator;
said equipment being characterized in that:- said detector-combined collimator (2,2a) is a rake collimator as claimed in any of claims 1-4, having its at least one raised wall (23,23a,b) parallel to the bed length;- the bed is positioned at such a distance from the collimator positions, that in each position the outer edge (extremity) of said collimator's raised wall is approx. 5 cm distanced at most from the patient's body on the bed; and- the bed is adapted (5,7) to allow movements vis-à-vis said detector-combined collimator in two perpendicular directions, both transverse to the bed length, viz. a sideward movement at position (a) or (b) of said at least one collimator, and an up- and downward movement at position (c) or (d) thereof. - An equipment for performing the method of imaging a target organ in a patient by SPECT, by using the so-called LOrA technique, comprising at least one detector-combined collimator, a bed (4) for a patient to be examined, and means for defining four collimator positions relative to the bed, essentially situated at the angular points of a square, viz. over the bed (a), under the bed (b), and on both sides (c) and (d) of the bed, which positions can be occupied by said at least one collimator;
said equipment being characterized in that:- said detector-combined collimator (2,2a) is a rake collimator as claimed in any of claims 1-4, having its at least one raised wall (23 ,23a,b) parallel to the bed length;- the bed is positioned at such a distance from the collimator positions, that in each position the outer edge (extremity) of said collimator's raised wall is approx. 5 cm distanced at most from the patient's body on the bed; and- said at least one detector-combined collimator is adapted (3) to allow movements vis-A-vis the bed in perpendicular directions, all transverse to the bed length, viz. substantially parallel to the bed surface in the positions (a) and (b), and substantially perpendicular to the bed surface in the positions (c) and (d). - Equipment as claimed in any of claims 7-8, wherein the equipment comprises one gamma detector provided with a rake collimator as defined in any of claims 1-4, which detector-collimator combination is equipped in such manner that it can be moved from position (a) to positions (c), (b) and (d), successively.
- Equipment as claimed in any of claims 7-8, wherein the equipment comprises two gamma detectors provided with rake collimators as defined in any of claims 1-4, which detector-collimator combinations are positioned opposite to each other, sandwiching bed plus patient in between, both equipped in such manner that they can be moved from position (a) to position (c), and from position (b) to position (d), respectively.
- Equipment as claimed in any of claims 7-8, wherein the equipment comprises four gamma detectors with rake collimators as defined in any of claims 1-4, which detector-collimator combinations are so positioned that they occupy positions (a), (b), (c) and (d), respectively, thereby sandwiching bed plus patient in between.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP01900144A EP1247280B1 (en) | 2000-01-14 | 2001-01-10 | Equipment for imaging by spect |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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EP00200130 | 2000-01-14 | ||
EP00200130 | 2000-01-14 | ||
PCT/EP2001/000188 WO2001052269A1 (en) | 2000-01-14 | 2001-01-10 | Method of imaging by spect |
EP01900144A EP1247280B1 (en) | 2000-01-14 | 2001-01-10 | Equipment for imaging by spect |
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EP1247280A1 EP1247280A1 (en) | 2002-10-09 |
EP1247280B1 true EP1247280B1 (en) | 2007-06-27 |
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EP01900144A Expired - Lifetime EP1247280B1 (en) | 2000-01-14 | 2001-01-10 | Equipment for imaging by spect |
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US (1) | US6967331B2 (en) |
EP (1) | EP1247280B1 (en) |
JP (1) | JP2003520348A (en) |
AT (1) | ATE365968T1 (en) |
AU (2) | AU2001223734B2 (en) |
CA (1) | CA2383122A1 (en) |
DE (1) | DE60129105T2 (en) |
WO (1) | WO2001052269A1 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
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DE10142421A1 (en) | 2001-08-31 | 2003-04-03 | Forschungszentrum Juelich Gmbh | Device for SPECT examinations |
EP1802998B1 (en) * | 2004-10-15 | 2014-09-17 | Koninklijke Philips N.V. | Detector for nuclear medicine |
US8242453B2 (en) * | 2004-10-15 | 2012-08-14 | Koninklijke Philips Electronics N.V. | Imaging system for nuclear medicine |
JP2008533455A (en) * | 2005-03-08 | 2008-08-21 | バン・ドウルメン,アドリアヌス・エイ | SPECT and / or PET imaging equipment |
US7635848B2 (en) * | 2005-04-01 | 2009-12-22 | San Diego State University Research Foundation | Edge-on SAR scintillator devices and systems for enhanced SPECT, PET, and compton gamma cameras |
US8232528B2 (en) * | 2006-09-19 | 2012-07-31 | Shimadzu Corporation | Nuclear medical diagnostic device |
US7825383B2 (en) * | 2006-09-21 | 2010-11-02 | Siemens Medical Solutions Usa, Inc. | Mobile camera for organ targeted imaging |
US7723674B2 (en) * | 2006-09-21 | 2010-05-25 | Siemens Medical Solutions Usa, Inc. | Attenuation correction for SPECT imaging using non-classical orbits of many small gamma cameras |
US7381960B1 (en) * | 2006-11-11 | 2008-06-03 | National Tsing Hua University | Imaging system and method for the non-pure positron emission tomography |
US20110110570A1 (en) * | 2009-11-10 | 2011-05-12 | Avi Bar-Shalev | Apparatus and methods for generating a planar image |
BR112014012015A2 (en) | 2011-11-22 | 2017-05-30 | Koninklijke Philips Nv | full body nuclear imaging system and method |
WO2013168111A2 (en) | 2012-05-08 | 2013-11-14 | Spectrum Dynamics Llc | Nuclear medicine tomography systems, detectors and methods |
Family Cites Families (10)
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AU5963890A (en) * | 1989-06-30 | 1991-01-17 | H. Charles Kaplan | Transmission/emission registered image (teri) computed tomography scanners |
JPH0462492A (en) * | 1990-06-29 | 1992-02-27 | Toshiba Corp | Nuclear medical diagnostic device |
JPH04297899A (en) * | 1991-03-27 | 1992-10-21 | Toshiba Corp | Manufacture of collimator, and collimator obtained thereby |
US5479021A (en) * | 1991-06-10 | 1995-12-26 | Picker International, Inc. | Transmission line source assembly for spect cameras |
US5434416A (en) * | 1993-03-24 | 1995-07-18 | Kabushiki Kaisha Toshiba | Method and apparatus for reconstructing SPECT image by utilizing two separate reconstruction filter functions |
WO1994025879A1 (en) * | 1993-04-27 | 1994-11-10 | Siemens Medical Systems, Inc. | High-sensitivity spect imaging of small body organs using a multi-head scintillation camera with non-uniform collimation |
US5602395A (en) * | 1995-10-02 | 1997-02-11 | Adac Laboratories | Gamma camera having partial septas and moving septas for positron emission tomography (PET) |
US5838009A (en) * | 1996-11-27 | 1998-11-17 | Picker International, Inc. | Variable angle multiple detector nuclear medicine gantry |
EP0898178A3 (en) * | 1997-08-19 | 1999-03-24 | van Dulmen, A. A., Dr. | Method of imaging by SPECT |
US6583420B1 (en) * | 2000-06-07 | 2003-06-24 | Robert S. Nelson | Device and system for improved imaging in nuclear medicine and mammography |
-
2001
- 2001-01-10 JP JP2001552400A patent/JP2003520348A/en active Pending
- 2001-01-10 WO PCT/EP2001/000188 patent/WO2001052269A1/en active IP Right Grant
- 2001-01-10 AU AU2001223734A patent/AU2001223734B2/en not_active Ceased
- 2001-01-10 AT AT01900144T patent/ATE365968T1/en not_active IP Right Cessation
- 2001-01-10 AU AU2373401A patent/AU2373401A/en active Pending
- 2001-01-10 CA CA002383122A patent/CA2383122A1/en not_active Abandoned
- 2001-01-10 EP EP01900144A patent/EP1247280B1/en not_active Expired - Lifetime
- 2001-01-10 US US10/181,211 patent/US6967331B2/en not_active Expired - Fee Related
- 2001-01-10 DE DE60129105T patent/DE60129105T2/en not_active Expired - Fee Related
Also Published As
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EP1247280A1 (en) | 2002-10-09 |
DE60129105D1 (en) | 2007-08-09 |
JP2003520348A (en) | 2003-07-02 |
DE60129105T2 (en) | 2008-03-20 |
AU2373401A (en) | 2001-07-24 |
US20030111608A1 (en) | 2003-06-19 |
US6967331B2 (en) | 2005-11-22 |
AU2001223734B2 (en) | 2005-03-24 |
CA2383122A1 (en) | 2001-07-19 |
WO2001052269A1 (en) | 2001-07-19 |
ATE365968T1 (en) | 2007-07-15 |
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